An insurance holding company based in Bermuda is investing $125 million in a rapidly expanding American underwriting platform as momentum in the managing general agent market continues.

White Mountains Insurance Group Ltd said it has completed a strategic structured capital investment in Bishop Street Underwriters.

Bishop Street, a portfolio company of RedBird Capital Partners, said it surpassed $650 million in gross written premium in 2025 and maintained a portfolio loss ratio below 50 per cent.

Chad Levine, chief executive of Bishop Street, described the deal as coming during a period of “unprecedented momentum” for the platform. He said the company plans to accelerate its strategy of backing specialist underwriting teams, pursuing acquisitions and launching new programmes in 2026.

Liam Caffrey, CEO of White Mountains, said Bishop Street was “quickly emerging as an industry-leading MGA platform” and added that the executive team had a strong track record of scaling insurance distribution businesses.

White Mountains is a Bermudian-domiciled financial services holding company listed on the New York Stock Exchange and the Bermuda Stock Exchange.

Bermuda’s MGA sector has grown in recent years as insurers seek specialised underwriting expertise and more flexible distribution models.

Bishop Street said the partnership would allow it to expand its global footprint and pursue further growth opportunities in 2026 and beyond.